/**
 * 获取顶级窗口dom
 * @param currentDom 当前窗口ycWindow.dom
 */
function dom_getParentDom(currentDom) {
    if (!currentDom.opener || !currentDom.opener.dom) {
        return currentDom;
    }
    return dom_getParentDom(currentDom.opener.dom);
}